<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="studentServlet" method="post">
  <input type="hidden" name="flag" value="enroll">
  账号<input type="text" name="username"><br>
  密码<input type="password" name="psw"><br>
  <input type="submit" value="注册">
</form>
</body>
</html>
